Unidirectional fiber materials are used in ballistic-resistant structures and are disclosed, e.g., in U.S. Pat. Nos. 4,916,000; 4,079,161; 4,309,487 and 4,213,812. A non-woven ballistic-resistant laminate referred to by the trademark “Spectra-Shield” is manufactured by Allied-Signal, Inc. The laminate structure is used in soft body armor to protect the wearer against high-velocity bullets and fragments. “Spectra-shield” was made by first forming a non-woven unidirectional tape, which was composed of unidirectional polyethylene fibers and an elastic resin material that held the fibers together. The resin penetrated the fibers, effectively impregnating the entire structure with the resin product. Two layers, or arrays, of the unidirectional tape were then laminated together (cross-plied) at right angles to form a panel. The panel was then covered on both sides with a film of polyethylene. The film prevented adjacent panels from sticking together when the panels were layered in the soft body armor. The final panel was heavier and stiffer than desired for use as a ballistic-resistant panel. The weight and stiffness were due in part to the penetration of the entire structure with the resin product.
Composite ballistic-resistant structures are disclosed, e.g., in U.S. Pat. Nos. 6,846,548 and 7,211,291, having a plurality of filaments arranged in a fibrous web that is held together in a unitary structure by a domain matrix. The domain matrix comprises a plurality of separated matrix islands that individually connect, or bond, at least two filaments, to thereby hold the filaments in a unitary structure. Portions of the filament lengths within the unitary structure are free of matrix islands, causing the domain matrix to be discontinuous. The composite may be formed into cross-plied structures.
Non-woven ballistic-resistant laminates without resins are disclosed, e.g., in U.S. Pat. Nos. 5,437,905; 5,443,882; 5,443,883 and 5,547,536. A sheet of non-woven ballistic-resistant laminate structure was constructed of high performance fibers without using resins to hold the fibers together. Instead of resin, thermoplastic film was bonded to outer surfaces of two cross-plied layers of unidirectional fibers to hold the fibers in place. The film did not penetrate into the fibers. A sufficient amount of film resided between the bonded layers to adhere the layers together to form a sheet. Bonding the two layers of unidirectional fibers cross-plied to one another was necessary to meet structural requirements of the ballistic-resistant panel, such as impact force distribution. The individual sheets were placed loosely in a fabric envelope of an armored garment to form a ballistic-resistant panel.
However, known ballistic-resistant laminates are limited in their ability to provide a light weight and flexible ballistic-resistant structure in either sheet or laminate form.